Users, such as when browsing a social networking site, may be presented in a stream of content items for the user's consumption. For example, a user may see a stream of content items containing photos posted by friends or family members, links to stories provided by friends or family members, videos posted for the user, etc. The content items in a stream may be presented in a chronological order, with the latest items displayed before items posted at a later point in time. As streams become larger, a purely chronological stream may not be an optimal stream for user consumption.
Some web-based applications provide information in the form of a stream to be viewed by users. Pagination of streams is accomplished by obtaining the results for a page and all previous pages, and discarding the results from the previous pages. Since streams are continuously populated; however, the content of the stream may change as a user scrolls down to a second page. For example, a new content item may be delivered to the stream when the user scrolls to the second page. Thus a current result of the first page may not resemble the results of a refreshed first page. Diversification processes may also be applied to a stream to modify the order in which the content items appear. While diversification may improve the user experience by prioritizing the display of certain content items in the stream, the diversion from a chronological order presentation as a result of the diversification poses a particular challenge for tracking which content items have been delivered and which have not, particularly when content items are provided for viewing as different pages.